Open-end rotor spinning devices of the above-indicated type typically comprise a cover element which seals a rotor housing during the spinning process by means of a lip seal in an airtight manner. The rotor housing is open to the front. The cover element comprises a bearing bracket for mounting an opening cylinder as well as bearing brackets for a swivel pin which are arranged orthogonally to the axis of the opening cylinder. A conduit plate adapter, which can be readily replaced, if necessary, is fitted into the cover element. The cover element is connected via this swivel pin to an associated spinning-box housing. Moreover, the opening-cylinder housing of a sliver opening device as well as the bearing housing of a sliver feeding cylinder are fixed on the cover element.
The individual fibers combed out of a feed sliver by the opening cylinder are transported via a so-called fiber guide conduit to the spinning rotor and spun by the spinning rotor into a yarn which can be continuously drawn off. As is known, for example, from German Patent Disclosure DE 197 12 881 A1, the opening-cylinder housing is connected to a receptacle in the cover element for the conduit plate adapter via a fiber guide conduit assembly which is formed in conduit sections. The fiber guide conduit assembly consists in its totality of two separate conduit sections, namely, a conduit section formed inside an insert portion of the fiber guide conduit assembly and another conduit section arranged in the particular conduit plate adapter.
When the engaged cover element is pivoted closed during the operation, the conduit plate adapter extends into the rotating rotor. It is assured in this manner that the mouth area of the fiber guide conduit is positioned sufficiently close to the fiber guide wall of the spinning rotor so that the individual fibers transported in the fiber guide conduit are fed onto the spinning rotor as prescribed. The conduit plate adapter also comprises a bore for fixing a yarn withdrawal nozzle adjacent to the mouth area of the fiber guide conduit.
The conduit plate adapter is coordinated for a certain rotor diameter. Thus, if, for example, it is necessary to replace the spinning rotor during the course of a change of a yarn batch, the conduit plate adapter must be replaced at the same time.
Open-end rotor spinning devices with such replaceably arranged conduit plate adapters are basically known and described, for example, in German Patent Disclosure DE 43 34 485 A1. In the spinning device of German Patent Disclosure DE 43 34 485 A1, the pivotably mounted cover element comprises an annular groove for inserting a lip seal element and a receptacle with conical contact surfaces which is open in the direction of the rotor housing. A conduit plate adapter is detachably fixed in this receptacle by means of screw bolts which extend through corresponding bores in the cover element and engage in fastening bores of the conduit plate adapter.
However, this type of fastening is disadvantageous in this known device since two machine screws must be removed in order to replace the conduit plate adapter, which is relatively time-consuming.
A similar open-end rotor spinning device is described in German Patent Disclosure DE 195 24 837 A1. However, the cover element in this device comprises a conduit plate adapter which is secured by a bar spring in the receptacle of the cover element. The conduit plate adapter can be rapidly and smoothly dismounted as needed by bending back the bar spring. In order to secure the conduit plate adapter, the bar spring fastened on one end to the fiber conduit plate engages in a tangential groove formed into the conical contact surface of the bearing body of the conduit plate adapter.
However, in practice, such a fastening method is only conditionally suitable for assuring a reliable seal of the conduit plate adapter which can be readily detached if necessary. An off-center introduction of force of the securing means can result, for example, in a tilting of the conical bearing body of the conduit plate adapter in the receptacle of the cover element with the consequence that problems with false air flowing can occur at the spinning devices.
German Patent Disclosure DE 198 36 073 describes an open-end rotor spinning device in which the detachable fastening of the conduit plate adapter on the cover element takes place in a non-positive manner via a magnetic coupling. That is, disk-shaped permanent magnets are introduced into the receptacle of the cover element which magnets correspond to a ferromagnetic component of the conduit plate adapter, preferably a steel disk.
This purely non-positive fixing of a conduit plate adapter in the receptacle of the cover element results in a simple fixing of the conduit plate adapter which can be readily and rapidly detached in case of need but is very reliable and exact during operation. However, in practice, the conduit plate adapter still needs improvement, especially in the area of the entrance of the fiber guide conduit.